Rheostat.



No. 728,978. PATENTED MAY 26, 1903;

' '0. J. REED.

RHEOSTAT.

APPLICATION FILED JUNE 3, 1902.

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, RHEOSTAT.

APPLICATION FILED mm: a, 1902.

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UNITED STATES Patented May 26, 1903.

PATENT ()FFICE.

CHARLES J. REED, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO SECURITY INVESTMENT COMPANY, A CORPORATION OF PENNSYL- VANIA.

RH EO STAT.

SPECIFICATION forming part of Letters Patent No. 728,978, dated May 26, 1903.

Application filed June 3, 1902. Serial No. 110,028. (No model.)

To all whom, it I may concern.-

Be it known that I, CHARLES J. REED, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Improvement in Rheostats, of which the following is specification.

My invention relates to adjustable resistance apparatus for electric circuits generally known as rheostats, and it has for its object to provide apparatus of simple and wellventilated construction the elements of which are so combined as to be susceptible of ready manipulation to obtain a uniformly variable resistance through a comparatively wide range. V

lWly invention is illustrated in the accompanying drawings, in which Figure 1 is a plan view, and Fig. 2 a transverse section, parts being in elevation and parts broken away. Fig. 3 is a perspective view of one of the circuit-changing devices, and Fig. 4 is a diagrammatic view of the resistance-circuits and means for varying the relation of said circuits.

My invention is susceptible of embodiment in apparatus of different forms in which the various elements are modified as to structural details and relative arrangements, and I therefore desire it to be understood that the illustration and description of details herein given are not to be regarded as limiting the invention to any specific construction and arrangement of apparatus except in so far as the prior development of the art imposes limitations.

As shown in the drawings, the frame 1 of the apparatus comprises a base-plate 2 and two end plates or standards 3 and 4, which may be of any suitable material.

Mounted in suitable bearings in the end plates 3 and 4 of the frame are two shafts 5 and 6, the former of which is provided with a suitable operating-handle 7. Rigidly mounted upon the shaft 5 are three disks 8, which may be of either non-conducting material or of conducting material, insulated from the shaft by means of suitable insulating collars or bushings. The disks 8 are shown as respectively provided with circumferential grooves 9, that are approximately semicircular in cross-section, and in the respective grooves are seated helical coils 10, 11, and 12, of German silver or other suitable resistancewire.

In case the disks 8 are not of non-conducting material the annular recesses 9 may be lined with such material in order to suitably insulate the coils 10, 11, and 12.

Mounted upon the shaft 5, adjacent to the respective disks 8 and suitably insulated from the shaft, are contact-rings 13, 14, and 15, with which engage, respectively, brushes 16, 17, and 18, that projectfrom posts 19, 20, and 21, supported upon the base-plate 2.

The shaft 6 is provided with disks 8, which are respectively provided with helical coils 10, 11, and 12, mounted in grooves 53*, all of said parts being duplicates of the corresponding parts mounted upon the shaft 5 and being also in alinement therewith.

The disks 8 and 8 are of such diameter that the corresponding coils 10 and 10, 11

and 11 and 12 and 12 intermesh with each other after the manner of the teeth of gearwheels, the turns of the respective helices being separated from each other a distance substantially equal to the diameter of the wire, so that as the coils intermesh they will make good electrical contact with each other.

The ends of each coil are fastened to the corresponding disk in a recess 12 by means of binding-screws 12 and 12 or other suitable fastening devices, and the screws 12 are connected to the corresponding contact-rings by means of conductors 12". The shaft 6 is also provided with'a set of contact-rings 13,

14, and 15, which are suitably insulated from the shaft and with which engage fingers or brushes 16, 17, and 18 projecting from posts 19 20 and 21, supported by the baseplate 2.

In order to change the circuit connections of the resistancecoils, I provide a sliding block 22, preferably of non-conducting material, on the bottom of which at one side I fasten a metal strip 23, provided with upwardlyprojecting arms 24, 25, and 26, at the extremity of each of which is a spring-finger 27. On the bottom of the block- 22 at the opposite side I fasten a similar metal strip 23, having upwardly-projecting arms 24, 25,

and 26, the extremities of which I provide with spring contact-fingers 27, the arms and fingers pertaining to each strip being so spaced as to correspond in position to the two sets of posts 19, 20, and 21 and 19, 20", and 21*. I also provide the block 22 with two transverse metal strips 28 and 29, each of which has spring contact-fingers 30 and 31 at its opposite ends, the distance between the strips 28 and 29 being the same as that between the posts 19 and 20 and also that between the posts 20 and 21.

The block 22 is so mounted as to be readily moved longitudinally and may be provided with a knob or handle 32, by means of which it may be moved.

The base-plate 2 is provided with bindingposts 33 and 34 for the purpose of connecting the rheostat to the circuit-in connection with which it is to be used. The binding-post 33 is joined to the post 19 by a conductor 35, and the binding-post 34 is joined to the post 21 by a conductor 36.

It will be seen by reference to Figs. 1 and 4 that with the strips 23 and 23 in the posi tions indicated in each of these figu res the resistance elements, each of which comprises two intermeshing coils, are connected in parallel.

By moving the block 22 inward the fingers 27 and 27 will be moved out of engagement with the corresponding posts, and a sufficient movement will bring the strip 28 into position to bridge the space between posts 19 and 20 and the strip 29 into position to bridge the space between the posts 20 and 21. With the parts in this position the resistance elements will be connected in series, as may be readily seen.

In order to secure the maximum amount of resistance from the rheostat shown, the handle 7 must be turned in a clockwise direction until the ends of the coils which are connected to the binding-screws 12 are in engagement and the block 22 be moved inwardly to put the resistance elements all in series. In this position of the parts it will be seen that current entering, for eXample,at the binding-post 33 will pass by way of conductor 35, post 1'9, brush 16, the entire length of coil 10, the entire length of coil 10, ring 13 brush 16", post 19, strip 28, post 20, brush 17, ring 14, the entire length of coil 11, the entire length of coil 11", ring 14, brush 17, post 20, strip 29, post 21, brush 18, ring 15, the entire length of coil 12, the entire length of coil 12, ring 15", brush 18, post 21 and out through conductor 36 and binding-post 34. By now turning the handle 7 in a contra-clockwise direction the several disks and intermeshing coils, acting in the manner of gear-wheels, will be turned, and thus gradually reduce the length of wire in circuit until the ends of the respective coils which are connected to the binding-screws 12 are in contact, when the entire resistance of the coils will be cut out.

The manipulation of the block for changing the connection of the resistance elements from series to parallel, and vice versa, may obviously be made at any time, and it will also be understood that the number of coils and the number and arrangement of circuitchanging strips and fingers may be such as to afford other combinations than those here specifically shown without departing from the invention.

I claim as my invention- 1. A rheostat comprising two disks having non-conducting peripheral surfaces and helical coils of wire so disposed upon said peripheral surfaces as to mesh with each other when either disk is rotated.

2. A resistance element comprising two intermeshing, annular helices of resistance-wire and rotatable supports therefor.

3. A resistance element comprising two intermeshing, annular helices of wire, rotatable disk-supports therefor and means for rotating one of said disks.

4:. A resistance element comprising two intermeshing, annular helices of wire, rotatable disks upon which said coils are mounted, brushes and contact-rings for conveying current to and from said coils and means for rotating one ofsaid disks.

5. In a rheostat, the combination with a plurality of pairs of intermeshing, annular helices of wire and their rotatable supports, of means for conveying current to and from the several pairs of coils and means for rotating one set of corresponding supports of the several pairs of coils.

6. In a rheostat, the combination with a plurality of pairs of intermeshing, annular helices of wire and rotatable supporting-disks, of means for conveying current to and from the several pairs of coils, means for rotating one set of corresponding disks and means for changing the circuit relations of the pairs of coils.

7. In a rheostat, the combination with a plurality of pairs of intermeshing, annular helices of wire and supporting-disks therefor, of means for conveying current to and from the several pairs of coils, means for changing their circuit relations and means for rotating one set of corresponding disks to effect progressive variation of the length of resistancewire in circuit. v

In testimony whereof I have hereunto subscribed my name this 19th day of May, 1902.

CHARLES J. REED.

W'itnesses:

RoB'r. B. FLETCHER, THOMAS B. SMITH. 

